Size Conversion

POPULAR ALTERNATIVE TIRE SIZES

For an equivalent size, a HIGHER load range tire can always be substituted:

• ST225/75R15 LR D Marathon substituted for ST225/75R15 LR C Marathon
• Match inflation pressure to load carrying requirements using load and inflation tables

Some manufacturers use slightly different size designations. Popular RV tire size equivalents:

235/80R22.5 = 245/75R22.5
255/80R22.5 = 265/75R22.5
275/80R22.5 = 295/75R22.5

CONVERTING FROM 8R19.5 TO 225/70R19.5:

Many RV owners are converting from 8R19.5 to the newer, more popular 225/70R19.5 size. In most cases this can be done successfully. The following guidelines should be consulted to determine if this conversion can work for you. Before making a final decision to convert, we recommend contacting your local Goodyear RV tire retailer to verify that all considerations have been met.

Advantages = more even wear, improved stability

Conversion Checklist (8R19.5 to 225/70R19.5 only):

1. Check with the vehicle manufacturer to ensure approval of the tire/wheel clearance and fitment
2. Verify that rim width is compatible to run the 225/70R19.5
3. A wider minimum dual spacing is required and should be confirmed
4. Due to a tire diameter and static loaded radius difference there will be an increased number of revolutions per mile which will mean that the vehicle speedometer and odometer will read approximately 2.5% high. Because the difference in RPM is less than 3%, however, no changes to gearing would generally be required.
   

*Measurements based on this rimmed width.